What does it mean to "undermine" something?

To "undermine" something means to injure or destroy it in a subtle or underhanded way. This term conveys the idea of eroding the foundations or stability of an entity, often without direct confrontation. The act of undermining typically involves covert actions that gradually weaken or damage the target, making it less effective or less stable. In various contexts, such as politics, business, or personal relationships, to undermine someone or something can mean working against them in a way that is not immediately evident, which can lead to long-term detrimental effects.

The other choices suggest actions that are positive or neutral—such as building support or strengthening—which are in direct contrast to the meaning of "undermine." Observing carefully does not relate to the concept of undermining, as it implies a careful examination without any intention to diminish or harm. Therefore, the definitions associated with those options do not align with the connotative and denotative meanings of undermining, making the correct choice clear.